


My medieval incest simulator is lewd as I expected

by theway



Category: Fire Emblem: If | Fire Emblem: Fates
Genre: Brother/Sister Incest, Dirty Talk, Erotica, F/M, Firsts, Foot Jobs, Incest Kink, Kissing, Post-Fire Emblem Fates: Conquest, Royalty, Sibling Incest, Swordfighting, Vaginal Sex
Language: English
Status: Completed
Published: 2018-09-01
Updated: 2018-09-01
Packaged: 2019-07-05 09:12:21
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,169
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15860646
Author URL: https://archiveofourown.org/users/theway/pseuds/theway
Summary: Growth rates come and go. But your big brother's base stats? Those are forever.





	My medieval incest simulator is lewd as I expected

**Author's Note:**

  * For [Kalloway](https://archiveofourown.org/users/Kalloway/gifts).



> I hope it's incesty enough for you, Kalloway-senpai. Post-Conquest campaign, and it's presumed Corrin and Xander have talked about their feelings a little, though not to the… extreme extent of their in-game S support.
> 
> This work is complete and won't receive further updates. To receive notifications about new works and chapters, you can subscribe [this RSS feed](https://vas.neocities.org/etc/ao3_works_feed.xml), or [my profile](/users/theway).

“Alright, boys, take ’em out!” the bandit leader yelled, and his group charged forth with a roar. The first jumped swinging his axe… and completely missed the mark.

“If you lay down your weapons, I promise you a fair trial,” Corrin said as she thrust her sword, shoving the blade between the axe’s blade and the handle, then moving upwards, sending it flying off the bandit’s grip and into the air.

“Die!”

“Oh, is that how we’re going to do it, then?” she said, kicking the bandit back; he fell on the ground, and then the blunt end of the handle fell on his head, knocking him out.

“You bitch!” another bandit yelled, taking his turn with his axe… completely missing the mark.

“You don’t have to be this way! I’m sure there’s many farms hiring muscle.”

“Die!”

“I’m starting to notice patterns in the vocabulary…,” Corrin thought aloud as she took hold of the bandit’s arm, bent it in an uncomfortable position until he dropped his weapon, then hit the back of his head with her pommel until he, too, collapsed.

“Take this!” a third bandit yelled, sure he’d be able to pull it off… completely missing the mark.

“Whoa, whoa, whoa!” Corrin exclaimed as the blade hit the ground, barely an inch from the body of the collapsed bandit. “No friendly fire allowed!”

“Di—”

“Let’s not get ahead of ourselves,” she interrupted him, quite sure of what he was going to say, and cut the axe’s wooden part in two. The bandit, having put all his weight on it, lost his balance, fell, hit his head on a rock, and collapsed. Head trauma was chic with ruffians in these parts.

“What’s going on?! What sort of demon are you?” their leader said from afar.

“Look, it’s a terrible idea to attack into hills. The probability of landing a hit is infinitesi—”

“You witch! Demon! No one’s ever survived a hit from my throwing club. Say your prayers!” he screamed, then threw his club. It spun around in the air… and was deflected by Xander. It flew off in a random direction, followed shortly by an “Ah!” at around the same time as it should have landed. Perhaps another unfortunate bandit had collapsed?

“You’re safe now,” Xander said.

“N-no way…!” the bandit leader said, relieved that at least he’d kept some distance between himself and the Nohrian royals. She’d have to come towards him to attack, and once she was out of those hills—

“Alright, here I go!” Corrin said as energy flowed through her sword.

“Oh, f—”

It was a Levin Sword. He might have miscalculated a thing or two.

The bandit leader was struck by a burst of lightning right on his chest, sending him flying up and back. Still in the air, limbs flailing wildly for nonexistent balance, Corrin noticed a weak point.

“Wait, no!” the bandit said, but Corrin couldn’t be stopped.

“Dye… your hair a different colour!” she shouted as she sent another surge of lightning between the bandit’s thighs, critically hitting his manhood for far too much damage. He suffered pain so great he’d fainted even before he’d reached the ground. “It doesn’t go well with your eyes.”

Corrin sheathed her sword and took in a deep breath, enjoying the smell of fresh grass and toasted flesh. “Ah, another job well done.”

“You hoarded all the enemies again, though,” Xander said. “Leave some for the poor folks.”

“Oh, are you feeling jealous, big brother? Me taking on all these big, burly men…”

“Of course not,” he said, but the speed of his response and his blush gave him away. “And could you afford to be a little more serious? We’re supposed to be on official business.”

“Ah, sorry,” Corrin laughed. “It’s bit a while since we’ve been bandit hunting, is all. What with your coronation and the constitutional treaties and everything…”

“Big sister!” Elise’s voice pierced through the air as she ran towards them. “We took care of things on our end. How many villains did you emasculate this time?”

“Elise! Be more mindful. You’re making it sound like Corrin has been doing it on purpose.” Xander scolded her.

“That’s easy for you to say. I’ve had to nurse 15 of them back to health since we’ve started.”

“I’m sure there’s an explanation,” he insisted, but it was Corrin who couldn’t contain her blushing this time.

“Maybe little Corrin is feeling frustrated?” Camilla offered, coming in from above. “She’s at that age, after all.”

“I’ve been in good spirits all day,” Corrin said.

“There’s many kinds of frustration, my dear,” Camilla said, making her sister’s blush even deeper.

“Camilla!” Xander said.

“Camilla!” Corrin said.

“Camilla?” Elise said, unsure of why they were all speaking simultaneously, but feeling like adding in her voice to the choir.

“Don’t shoot the messenger,” Camilla shrugged.

“A-anyway,” Corrin cleared her throat. “If you’re all done, we should report back to the village and help Elise out with the rejuvenating.”

Perhaps it wasn’t the brightest or safest idea to have the royal family and their retainers to roam the land, hunting thieves, bandits, pirates, and assorted mischief makers, but it was invaluable in lifting people’s spirits up, and during the first few transitional years after the Great War, it was paramount that Nohr’s image be reconstructed, both in their own domain and for their neighbours’ sake.

To claim it was purely selfless would be a lie, however; many in the Nohrian army had grown a liking for these acts of heroism, and combat served as a reminder of the bonds they’d formed next to each other’s shoulders, watching each other’s backs. Plus, Corrin would hate to see Xander, one of the greatest swordsmen she’d known, degenerate on a throne, signing papers away all day.

She’d persuaded Jakob to etch his signature on a metallic plate, and he’d obliged. That alone had stopped his fingers and wrist from feeling sore every day, and it only became easier when Leo offered his insight on the wonders of decentralised administration, reducing the paperwork that had to go through Xander in the first place. The sudden organisational shifts weren’t taken by everyone with equally good faith; abuse was an issue, and Leo was off on campaigns of his own to persuade unruly dukes. The negotiations were aggressive more often than he’d liked, but purging out corruption wasn’t an entirely unpleasant affair for him.

The people, at least, were very pleased. That evening, the villagers threw them a feast in celebration.

“Oh, thank you, your highness,” an old woman said, shaking Xander’s hand. Her voice was raspy and small, but the sheer relief had brought years of life back to her. “Those bandits have been ravaging our fields for a long time now. We couldn’t have done it without you!”

“It’s my duty to serve. It wouldn’t have been an issue with more regular patrols in the first place; I’ll see that these mistakes won’t be repeated.”

“You’re our youngest king yet, but I feel like these are the brightest days for Nohr. The light of hope is shining again.” Xander nodded, accepting the compliment without sounding too proud or too humble. “If it wouldn’t be too rude to pry, has any fair light caught your interest as well?”

“Ah, um…” It took him a moment to see through that euphemism, and even longer to manage an answer. Guess it was true what they said about old women from farming towns and gossip, then. His gaze drifted towards Corrin, having a… colourful argument with Elise and Silas. “It’s… complicated.”

“There are many who would want your audience, your highness. One need not look far.”

“I’ll take your wisdom into consideration.”

He wondered what she was getting at. Had he been so obvious? Or was he reading too much into an excitable old woman? She _was_ around that age, as Camilla would say. He decided to think on it more later, over some sword swinging. Although he didn’t fancy war, he hadn’t realised how much he’d missed being out and about until he’d got a taste for it. He made a mental note not to protest Corrin as much the next time she brought up the subject.

* * *

“Letting off some steam?”

“Ah! Corrin!” Xander jumped. “I didn’t notice you were there.”

“Lost in thought all alone…,” Corrin mumbled. He was practising by himself just outside the accommodations graciously given to them by the village so they wouldn’t have to camp overnight; a déjà vu if she’d ever seen one.

“Come again?”

“It’s nothing. It’s good to see you haven’t lost the touch.”

“Would you like to join me?” Xander offered. “Is that why you came?”

“You’re stiff again, though. Is something on your mind, big brother? You weren’t like that earlier today. It’s only now that…”

“No, of course not,” he deflected the comment.

Corrin didn’t pry, instead walking closer to him, looking at the scenery. The hilly terrain, coupled with the wheat fields and the setting sun were quite the sight. She could make out the sounds of a long day coming to an end, equipment and livestock being returned to their storing places. Days like these, she realised that Nohr, too, was capable of much beauty; that the kingdom of dusk wasn’t destined to be bleak until the end of time.

“It’s nothing. It’s silly,” he added as the silence grew too awkward.

“I thought we’d said we’d be more open with each other.” She wasn’t facing him, still eyeing the horizon, where the green met the red. Her fingers were locked behind her. “Didn’t we?” she added, turning to look right into his eyes. From that angle, it looked like half her face was on fire.

“Yes, I know. I understand.” Xander sighed and seethed his sword. “It isn’t like before. It’s… awkward.”

“Whatever made you think I’d discard the awkward Xander woes? Give them all, so I’ll make a collection. Right?” She smiled.

“If you insist.” Xander walked up to her and stood by her side, enjoying the scenery with her. “I was thinking about marriage.”

“Oh. That.” She tried to distract herself to mask her discomfort. He wasn’t lying about it being an awkward topic, but she wasn’t about to turn him away after she’d convinced him to open up. “Well, you’re still young. There’s no rush.”

“No,” he shook his head. “I understand that. That’s not what’s bothering me. I already…,” he trailed off, then looked at his feet.

“It’s me, isn’t it? Is that what’s bothering you?”

She was looking at him. He raised a hand and brushed against her cheek. She turned it to the side, mashing it between her face and her shoulder, trapping it there. “I like you, Corrin. Of course I do. When I’m with you, I—” he took a moment to catch his breath, collect his thoughts. “No one else has made me feel that way. You’re strong, and capable, and I love being with you.”

“ _But_ ,” Corrin said in anticipation.

“But… But I’m torn over how to feel about you.”

Corrin was puzzled. “What do you mean?”

“Ever since we first met, I saw you as my little sister.”

“You’ve been a great big brother. The best big brother a little sister could ever hope for!” Praising him, Corrin sounded elated.

“These new feelings… they haven’t replaced the old ones. I still think of you as a little sister, and now also as a partner. I feel conflicted. It doesn’t feel right, thinking of family that way, but not thinking of family as family no less wrong.” Corrin giggled, which felt like an inappropriate reaction to him laying his insecurities out bare. “What?”

“You should hang around Leo more, big brother.” It was Xander’s turn to be puzzled; his expression closely mirrored hers. “Think outside the box. It isn’t about family versus love, it’s about family love.” Before he could respond, she stepped closer to him, whispering in his ear. “A big brother should love his little sister, should he not?”

“C-Corrin!”

Closer still, she pecked him on his cheek. “It’s getting dark. Nobody would think twice if we wanted a good night’s sleep after a hard day’s work.” She looked at him, and he looked back, and in her eyes, behind the usual affection, was something carnal and deeply flattering, for that was a look reserved for him.

“I do love my sister very, _very_ much,” he whispered back, “and not a day goes by that I do not think of her.”

“It is good to keep family in one’s mind, several times a day.” Xander turned his head, amused and surprised in equal measure. “Camilla maintains an interesting library; I hear only Nyx’s bests it.”

He looked around, reminding himself that this wasn’t the most private location. “We should… hurry inside,” he said. _Before we do something we regret_ , he added mentally. He took hold of Corrin’s hand and rushed into the building, walking as fast as he could without making it look like he was running for his life. Though as far as his body was concerned, he might as well be. They made their way through the inn and entered the first empty room they could find. Corrin locked the door behind them as Xander tried to cool down, but it didn’t last; as soon as she was done, she pounced him, pressing her lips on his. It was amazing how he managed to maintain his balance.

In all of those years, locked in that castle all by herself, she never could have imagined ever embracing Xander like that. His sweet, brotherly taste, the man she’d lost so much sleep over, who’d kept her company in the worst of times, who’d been by her side for all of it.

She broke their kiss, but their saliva was still connected; she gathered it up with her finger. “I love you, big brother, but it’ll be hard showing you how much exactly through the armour.” She began unfastening hers, trying her best not to toss everything aside haphazardly. Xander was more hesitant, but he followed suit; he found it surprising that she might actually be the more eager—and hornier—of the two, but it had its charms too.

Once nude, Corrin lay down on the bed, carefully positioning her limbs so as to obscure her more intimate parts, playing into what he wanted to see, what he was so close to seeing, but he was still denied. He wasn’t as seductive; she followed his well-defined chest down to his abdomen, and then lower to his indubitably excited member.

He joined her and crawled up to meet her eyes, brushing aside a lock of hair to have a better look of her face. Her pale skin, the result of so many years wasted in that prison, was painted in most beautiful crimson, a blend of shyness and arousal. “I’m lucky to have your love,” he said.

“But not as lucky having yours.”

“I don’t think we’ll ever see the end of that argument.” He could already see the words forming in her mouth, more tease than debate; he leaned in to kiss her, bringing an end to that. Opening her mouth, Corrin welcomed Xander’s intrusion, very eager to suck on her big brother’s fluids, an intoxicating incestuous taste that shut her mind off. Like for him, her sense of family collided with her love, fusing into an even more powerful bond; she welcomed its sinfulness and revelled in its taste. All those years ago, when he was the only thing that kept her company, when he kissed her good night, everything was so pure and innocent, making this corrupt encounter all the more palpable.

She couldn’t remember when her feelings had first shifted. Perhaps they had always been that way; a little sister desperate to be loved by her brother. She kissed him back, her tongue the invader now, and Xander was not at all displeased. Everyone in the kingdom knew him as the brilliant, young king, the upstanding youth that would bring Nohr forth into a new era, but they didn’t know of this side. This one was hers. Who knew how long he’d struggled with loving her? With his sloppy, wanton kiss, he hinted at notable frustrations of his own. She liked this dirty, dirty Xander.

As if reading his mind, he took his licking on a journey downward, tracing the length with kisses on her cheek, her neck, her collarbone, and finally…

“Haha!” Corrin laughed to the tickling sensation on her nipple. “No matter how old you get, men are always little boys, aren’t they?”

“You’re no embodiment of maturity yourself,” Xander replied without shifting his focus, proceeding to cup her breasts, feel their shape, their texture, their softness.

“Excuse me for not matching up to the family. The standard is set very high.”

“Oh, don’t worry, you’re very adorable over here. The contents you should be worried about are higher up.” He licked around her areola, then lightly brushed his teeth against her nipple, so she could feel something hard touching her, but not hurt her.

“You… ah… you dummy!” She slapped him on his head, but it didn’t come out as faux-offended as she’d liked, what with her feelings of pleasure building up in her, making their way out through her mouth. “That was just the worst. Where do you learn these terrible, terrible—ah!”

She would have loved nothing more than to chastise him all night long, but Xander had other priorities, and he’d located a weak point. Smacking him on the head, as righteous as it felt, wasn’t going to change his mind, unless she smacked him _really_ hard, but that would break the purpose of dragging him here to lay with him.

Being under him, she was at a disadvantage. She had to think out of the box, consider a different vector of attack, get her head out of the gutter and stop thinking in Leonese during sex. It was admittedly difficult with her nipples on fire and her brain spinning in pleasure, but if they could spar as equals in the fields, by Nohr, so too would they in the bedroom. Between outbursts of pleasure and half-silenced moans, she had an epiphany. Raising her legs, she brought her feet to Xander’s groin, not really striking him, but touching him, pressing her soles against him.

It brought a pause to Xander’s assault, empowering Corrin. _Aha_! “Don’t tease your little sister too much, unless you want to be teased back!” she proclaimed, a peculiar mix of cuteness, threat, and naïveté. She moved back and forth along his length; she could feel his warmth and size sandwiched between his abdomen and her feet, it aroused her own curiosity, very much interested in her brother’s body. “If you keep it up, I’ll keep stepping on you, which would be terrible…” Spirit left her words as she felt him hardening and twitching.

“Ah! No way!” she exclaimed.

“Um.”

“You feel good with… this? Camilla’s books spoke nothing of it!”

“Maybe you should have read Nyx’s?” Xander suggested awkwardly, unsure of what to make of Corrin’s surprise. “Don’t protest too much; you don’t look unhappy either.” They stared at each other in silence, finally nodding in mutual agreement that the Nohrian family were all irreparable perverts.

Corrin stopped teasing her brother with her feet, and, after getting in a more comfortable position, replaced them with her hands. She wasn’t unfamiliar with Xander’s body, considering how much time they’d spent training together, but it was the first time she’d seen him fully bare. Ever since he first confessed his feeling during the war, her fantasies veered off in wild directions, and she’d spent considerable time trying to visualise him with her fingers, but she’d clearly underestimated him.

“Ah… You’re pretty big,” she said, her face now a tomato from the previous activities and the increased intimacy.

“Am I? Thank you.” It had sounded like a compliment, though she hadn’t planned it out like that. She played around with his shaft, exploring its shape, its curves, the heat emanating from it. “I’m not made of glass, you know,” Xander said, commenting on her featherweight, almost fearful touch. Emboldened by his words, she used more pressure, stroking him, feeling his skin stretch and contract, his foreskin covering and uncovering his glans.

“I’m not the most experienced I could be…,” she admitted.

“That’s nothing to be ashamed of,” he said, stroking her cheek. “It’s okay. Tell me if it hu—aaah!”

His words were cut short as Corrin assaulted his testicles, squeezing them in a manner that most definitely wasn’t featherweight. “ _I’m_ not made of glass either.”

“Okay, but you don’t have to feel like—”

“What I feel like is making incestuous love.” To prove her point, she stopped fondling Xander’s cock, lay down, and spread her legs just enough to make it obvious. “And I expect to be stuffed full of my big brother’s cock.”

Xander didn’t know how much of it was acting to calm her own nerves, and how much her genuine feelings; probably a mix of both. He trusted her enough not to pretend everything was good even if she was in agony, so he would allow her a harmless, white lie. Besides, she was gushing so much down there, she was as ready as she could ever be, so there was no reason to be paranoid.

He lined his member up for penetration, even as he leaned up closer to her. As he pressed his hips forward, and his head touched her entrance, her lips parted with minimal resistance, opening up to welcome him into her warm, wet hole. Corrin inhaled and exhaled sharply, experiencing a flurry of new emotions, and the fulfilment of desires too old to remember not having them, even if their intensity had grown exponentially over the past year.

“The little princess has a very big mouth,” he said close to her ear, and he could feel the response immediately, both in how her vagina constricted around him, and the unintelligible movement of her hands on his back. “And a very dirty ear as well?” he offered and entered her fully, not a fraction of him outside, their bodies completely connected at last.

She nodded furiously. “I love… Big brother…” Her breathing got in the way of speech, but the message got across perfectly nonetheless. Xander moved slowly out of her, relieving a great pressure that built up in her, and which she immediately missed. Thankfully, he didn’t leave her hanging for long, as he entered her once again, warmer and wetter than before, and clinging on his cock like a vice.

“I would have thought little princesses fancied innocent tales of heroism. To think ours was most interested in keeping the bloodline pure…,” he said as he was fucking her; she crossed her hands around his back, and locked her legs behind him, pressuring him forward. She snuggled closer to him and kissed his neck, again and again, more force into it each time.

“I love you so much. Is it so bad?”

“You’re a dirty sister, and it fits you very much.” His thrusts were faster now, more powerful; she could feel it when their bodies collided, could hear the sounds of their wet skin, could smell his sweat, mixed up with hers, a very sensual and—yes—dirty experience.

“You’re a dirty brother, too…,” she murmured when she found the breath to. “To fuck your little sister like that… Weren’t you supposed to be a role model?” He did feel protective towards her, and that only made being with her more arousing; he wasn’t preparing her for the rest of the world, so she could be with others. He was doing it for himself, so he could have her. His little sister that he cared so much for, that he’d nurtured for so many years, that he wanted so carnally.

Corrin could feel the ripples of their motions all the way to her cervix, a warmth enveloping her entire body. “Xander…!” she said, and he knew what it meant. Soon after, he felt it, too, through the new, strange tightness in her vagina, as if it was trying to milk him. He let it happen, bringing forth his own orgasm, thrusting one last time in her before ejaculating. Her grasp tightened around him, around his neck and his hips, her full strength used to forge an inescapable prison, or perhaps a protective veil—it was hard to tell.

He collapsed on top of her, and after a few breaths took her face into his hands and kissed her everywhere he could find; cheek, ear, forehead, it didn’t matter much. She broke her embrace and reached for his hand, crossing fingers with him. They looked at each other until their eyelids grew too heavy and they had to sleep, happy to be each other’s final, and most important conquest.

**Author's Note:**

> Little sisters are the best.


End file.
